This invention relates generally to the field of vacuum brake boosters for cars or light trucks, and in particular, to an apparatus and method of attaching a tube member to a housing of a vacuum brake booster.
Vacuum brake boosters are typically used in automobiles and light trucks. They typically include a housing that includes a front side and a rear side. The rear side is attached to the firewall of the vehicle, while the front side provides an attachment for a master-cylinder.
Screws or tie-rods are commonly used to attach the booster to the firewall. They are typically crimped or welded to the inner side of the rear shell of the booster housing. The booster is presented to the firewall, and the screws or tie-rods (there are usually 4 screws or 2 tie-rods) are inserted through holes in the firewall. An operator then positions nuts on the other side of the wall (i.e. the driver""s compartment) and installs them on the screws or tie-rods. Although this is a widely used process, it involves two operators, one on each side of the firewall, and results in increased costs.
Another process for attaching a booster to a firewall of a housing involves only one operator. This process uses rigid tubular members that extend through the front side of the housing, through the interior of the booster and through the rear of the housing. Fastening bolts can then be inserted into the tubular members to allow the booster to be attached to the firewall. In this scenario, the nut is typically welded onto the firewall.
Various attempts have been made to attach such tubular members to the housing of vacuum brake boosters. An example of a conventional arrangement is described in EP 0 623 081 and shown generally in FIG. 10. As shown in FIG. 10, at least four parts are required, namely, a tubular member 100, a fitting 102, a nut 104 and a seal 106. One end 108 of tubular member 100 is connected and sealed to the front side 110 of a housing 112 via fitting 102 by slightly deforming the metal structure of fitting 102. That is, end 108 of tubular member 100 is crimped against fitting 102, which itself is crimped against the front side 110 of housing 112. The nut 104 and seal 106 are positioned adjacent an inner surface 114 of a back side 116 of housing 112. Nut 104 and seal 106 facilitate the connection and sealing of a second end 118 of the tubular member 100 to the back side 116 of housing 112. The seal is typically obtained by applying glue to a portion of a thread 109, which constitutes an additional step in the process and results in additional costs.
There are several disadvantages to this arrangement, including the large number of parts required (i.e. fitting 102, nut 104, seal 106, and tubular member 100). In addition to the steps required for sealing, the large number of parts increases the costs associated with the vacuum brake booster. Moreover, the installation of these parts is a labor intensive and time-consuming process, which also increases the costs associated with installing the booster.
Another example of a conventional apparatus is shown in FIG. 11. As shown in FIG. 11, a tubular member 200 consists of a first tube portion 202 and a second tube portion 204. The first tube portion 202 is linked mechanically to a rear housing 206 and the second tube portion 204 is linked mechanically to a front housing 208. A bolt 210 may extend through tubular member 200 from the front housing 208 to the rear housing 206. A flange 212 positioned adjacent to an end of bolt 210 prevents the master-cylinder from compressing the booster. EP 0 331 535, for example, discloses a similar arrangement for providing a tubular member in a vacuum brake booster.
There are also several disadvantages to this arrangement. For example, it is very impractical and difficult to manufacture and assemble the first and second tube portions 202, 204 so that they are a part of the housings 206, 208, respectively. This arrangement is also likely to require additional parts. The large number of parts required and the complexity of the interconnections between parts result in increased costs.
In addition to the above, attempts have been made to install metal tubes, studs, etc. onto a planar metal sheet by deforming the metal tube. Although this method of fastening materials together is well known, and is used in many other applications, it has not yet been applied to the manufacture and installation of vacuum brake boosters. In particular, this technique has not yet been utilized to address the problems associated with attaching tube member to a housing of a vacuum brake booster.
Accordingly, it would be desirable to have an apparatus and method of attaching a tube member to a housing of a vacuum brake booster that overcomes the disadvantages described.
One aspect of the invention provides a connector apparatus for attaching to a housing of a vacuum brake booster. A tube member includes a body portion, an outer surface, a first end, and a second end. A first collar portion is formed between the first end and the body portion and extends outward from the outer surface. A lip portion is formed at the first end and extends outward from the outer surface. The first collar portion and the lip portion define a recess to receive a first housing member. The first collar portion may preferably be adjacent to the first end of the tube member. The first collar portion may preferably include a body portion that extends outward from the outer surface in a direction towards the first end. The first collar portion may preferably have a conical shape. The tube member may further include a second collar portion spaced apart from the first collar portion. The second collar portion may preferably extend outward from the outer surface and may define a contact surface for contacting an inner surface of a second housing member. The second collar portion may preferably extend outward substantially perpendicular from the outer surface of the tube member.
Another aspect of the invention provides a method of attaching a tube member to a housing of a vacuum brake booster. A first housing member including an inner surface, an outer surface, and an opening formed therein is provided. A tube member including an outer surface, a first end, a first portion, and a body portion is also provided. The first portion of the tube member is positioned between the first end and the body portion. The first end of the tube member is inserted through the opening in the first housing member. A force is applied to the first end of the tube member. The first portion is deformed to create a first collar portion extending outward from the outer surface. The first collar portion is contacted against the inner surface of the first housing member. A second force is applied to the first end of the tube member. An end portion of the first portion is deformed to create a lip portion extending outward from the outer surface. The lip portion is contacted against the outer surface of the first housing member to create a seal between the first housing member and the tube member. The first collar portion may preferably be located adjacent to the first end of the tube member and may preferably include a body portion that extends outward from the outer surface in a direction towards the first housing member. The first collar portion may preferably have a conical shape. The first portion may preferably include a first wall thickness and the body portion may preferably include a second wall thickness, the first wall thickness being less than the second wall thickness. The first housing member may preferably include a flange portion, and the first collar portion may be contacted against the flange portion. The lip portion may preferably be contacted against the flange portion. The flange portion may preferably be angled with respect to the first housing member, and the first housing member may preferably be a planar member. The tube member may further include a third portion that is disposed between the body portion and a second end of the tube member. The third portion may preferably be deformed to create a second collar portion that extends outward from the outer surface. The second collar portion may preferably be contacted against a second housing member to create a seal between the tube member and the second housing member. The second housing member may preferably include an inner surface, and the second collar portion may preferably be contacted against the inner surface of the second housing member. The body portion may preferably include a second wall thickness and the third portion may preferably include a third wall thickness. The third wall thickness may preferably be less than the second wall thickness. The second collar portion may preferably extend outward substantially perpendicular from the outer surface of the tube member.
Another aspect of the invention provides a connector apparatus for attaching to a housing of a vacuum brake booster. A tube member includes a body portion, an outer surface, a first end, and a first portion for creating a collar portion extending outward from the outer surface. The first portion is disposed between the first end and the body portion. The first portion includes an end portion for creating a lip portion extending outward from the outer surface. The collar portion may preferably be adjacent to the first end of the tube member. The first portion may preferably include a first wall thickness and the body portion may preferably include a second wall thickness. The first wall thickness may preferably be less than the second wall thickness. The tube member may further include a third portion for creating a second collar portion that extends outward from the outer surface. The third portion may preferably be disposed between the body portion and a second end of the tube member. The body portion may preferably include a second wall thickness, and the third portion may preferably include a third wall thickness. The third wall thickness may preferably be less than the second wall thickness.
Another aspect of the invention provides a vacuum brake booster including a housing member having an outer surface and an opening formed therein. The housing member includes a flange portion surrounding the opening. A tube member includes a body portion, an outer surface, a first end, and a second end. A first collar portion is formed between the first end and the body portion, and extends outward from the outer surface of the tube member. A lip portion is formed at the first end and extends outward from the outer surface of the tube member. The first collar portion and the lip portion define a recess receiving the flange portion of the housing member. The lip portion may preferably lie in a plane of the outer surface of the housing member that is adjacent to the flange portion. The flange portion may preferably be bent inward from the outer surface of the housing member. The inner surface of the lip portion may preferably contact the flange portion. An outer surface of the lip portion may preferably be flush with the outer surface of the housing member.